Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		boolean[][] s=new boolean[h+2][w+2]; 
		int all=0;
		for(int i=1;i<=h;i++) {
			String S=sc.next();
			for(int j=1;j<=w;j++) {
				s[i][j]=S.charAt(j-1)=='.';
				if(s[i][j])all++;
			}
		}
		boolean dp[][]=new boolean[h+2][w+2];
		dp[1][1]=true;
		for(int t=1;t<h*w;t++) {
			boolean next[][]=new boolean[h+2][w+2];
			for(int i=1;i<=h;i++) {
				for(int j=1;j<=w;j++) {
					next[i][j]=s[i][j]&&
							   (dp[i-1][j]||
							    dp[i+1][j]||
							    dp[i][j-1]||
							    dp[i][j+1]);
				}
			}
			
			if(next[h][w]) {
				System.out.println(all-t-1);
				return;
				}
			dp=next;
		}
		System.out.println(-1);
		}
}